A decade ago, it would have been rare to meet someone who could carry out their profession from anywhere. For most, “going to work” involved physically going to a place of business. Today, because of the swift development of collaboration tools and the ubiquitousness of connectivity to the internet, working from anywhere is not only an option, but is often preferred by both employer and employee. Studies have shown that a mobile workforce tends to be more productive and experience higher job satisfaction.Voice over IP (VoIP) technology is one of the major facilitators of employee mobility. Here we highlight some of the functionalities and tools that allow for a seamlessly mobile workforce.

SIP client on your phone. Both Android and iOS mobile phones have many free SIP clients available for download from their respective app stores. A SIP client allows you to register your mobile device on your SIP server (that is, your IP PBX) via your data connection or Wi-Fi and have the internal extension of your office desk phone ring on your mobile phone. You can also provide your mobile device with a unique internal extension, essentially supplying your office with an additional telephony device. With the appropriate network configuration and security, this extension can be used from anywhere in the world as long as your phone is connected to the internet.Follow me.This is a feature that allows someone to call a single phone number and have that number ring either on your office desk phone, your mobile phone or any other phone you choose, depending on where you are at the time. This could function either as a hunt list, where each of these phones would ring in sequence if not answered after a predefined amount of time, or you could manually set your location so that the call will terminate on the appropriate phone. Some advanced systems can even use information from the GPS of your mobile phone to determine which phone should ring.Teleconferencing. SIP is a protocol that supports both voice and video. As such, it can be integrated into a teleconferencing or even a telepresence system. With the appropriate hardware, a teleconferencing system can interconnect multiple endpoints regardless of the capabilities of each. For example, a videoconference can take place with one location having a full audio/video system, another participant using her mobile phone via the internet with both audio and video, a SIP phone user connected via voice only, and a PSTN user that has called in using his telephone.

Roaming headsets. Headsets are used with many types of devices, including mobile phones, desktop phones, computers, tablets, car audio systems and televisions, to name a few. A single wireless headset that can connect to all these devices can vastly simplify their use while providing a simpler teleworking experience.Unified Messaging.This feature provides a single interface for accessing all types of electronic messaging including email, fax, text, voicemail and others. All of these messages can be sent via email, thus giving you only one interface to check for all of the messaging services. Adding features such as text-to-speech will allow you to literally hear your faxes or listen to your emails while driving, for example.

Hot desking. Closely related to extension mobility, this feature allows you to log into the IP phone at any desk and obtain your personal extension on that phone. This includes all of your settings such as speed dials, ringtones, number of rings before going to voicemail, and even the brightness of the display.

Security ConsiderationsIt is important to note that, as useful as these functionalities are, they must be employed with caution. Because many of these features function outside of the relative safety of the corporate network, it is vital that the appropriate security measures be taken to mitigate potential security threats. These may include:

The use of VPNs to connect mobile phones that register with the SIP server through the internet.

The employment of the appropriate firewall configurations on the edge of the corporate network that will perform deep inspection of packets to verify their source and type.

The implementation of measures to avoid toll fraud from users of internal extension numbers on their mobile phones.

The configuration of encryption for all voice communications to eliminate the possibility of eavesdropping, either from inside or outside of the corporate network.

CONCLUSIONVoIP technologies enable a more productive, more mobile workforce in multiple ways. As more and more employers realize the benefits of working remotely, we can expect a steady increase in the implementation of these technologies worldwide.

For networking professionals, one of the most difficult things to deal with is troubleshooting VoIP issues, because the troubleshooting process for VoIP is not always intuitive. Answers to the questions, “What could be wrong?” and “What should I check first?” are not always readily apparent.To aid your troubleshooting and allow you to take some meaningful actions before reaching out to your telco or vendor help desk, we’ve listed the most common VoIP problems you may face, as well as their causes and solutions.

Voice and data are differentAlthough it uses the same infrastructure as conventional data communications, voice over IP behaves differently on the network and has very different requirements. This is why it is often challenging for those accustomed to troubleshooting data network faults to pinpoint problems that may arise with voice services, even though the network seems to be working “just fine.”The good news is that today, VoIP is a mature and dependable technology whose kinks have largely been ironed out and dealt with. Chances are that any problems you may face have already been faced and solved by other networking professionals in the past.

Blocked portsSome of the most common VoIP issues involve the blocking of TCP and UDP ports. Ports are the addresses employed on the Transport Layer of the OSI model that are used on a device to distinguish between applications and services. Various voice services use specific ports to function. If these ports are blocked at any point between the communicating devices, voice services may fail partially or completely. Depending on what ports are blocked, different functionalities of VoIP will be affected.The location on the network where ports are most commonly blocked is at the network edge; that is, the point where the enterprise network meets the ISP (internet service provider) and the internet. At this location, there may be several mechanisms being employed such as access lists, firewall rules, or network address translation (NAT) that may be responsible for blocking ports. These services are all vital to the functionality and security of a network; however, they can also be the cause of VoIP failure.Access lists (ACLs) – ACLs are rules found on the edge device of an enterprise network (a router or a firewall) that block or allow packets based on their source and destination IP addresses and ports. If ports that VoIP services require are blocked, then calls or registration may fail.Firewall rules – Firewall rules go one or more steps beyond simple ACLs. Firewalls are able to inspect each packet that attempts to enter the enterprise network and to decide, based on specific security policies, which packets will be allowed, and which won’t. Other than source and destination IP addresses and ports, firewalls can look deeper into a packet and determine if it is safe to let the packet through or not. If a firewall is not configured to allow voice services to pass, a failure can occur.Network address translation (NAT) – NAT has been the great deliverer when it comes to delaying the inevitable exhaustion of IPv4 addresses. By providing a translation from internal private IP addresses to external public IP addresses, it allows for the reuse of IP addresses within enterprise networks without any danger of conflict, thus giving several more years of life to the IPv4 addressing scheme. At the same time, it can be a nightmare for VoIP as it often causes problems with voice calls, especially those that are initiated from the outside. Elaborate best practices have been devised and have even been written up in an RFC to define NAT traversal practices for SIP-based voice communications.

Voice services affected by blocked portsDifferent ports being blocked may impact voice services in different ways. This depends on what part of a voice service is being blocked.Signaling - VoIP most commonly uses the Session Initiation Protocol (SIP) for signaling. What is often misunderstood is the fact that SIP does not carry any voice packets. It is used to initiate a call, send ringtone, provision bandwidth, and to establish services like conferencing, call waiting and call park, to name a few. If SIP ports are blocked, no calls can be initiated, the IP PBX cannot register with the SIP trunk, and telephony endpoints cannot register with the IP PBX. The default ports that SIP uses are 5060 and 5061.Voice traffic – IP telephony traffic is carried by Real-time Transfer Protocol (RTP) and is monitored by RTP Control Protocol (RTCP). RTP and RTCP typically use UDP ports somewhere between 1024 and 65535. The specific ports that are used depend on the configuration of each IP PBX, IP phone and SIP trunk, and are largely defined by each individual vendor and telco in their own systems. If these ports are blocked, a call may actually connect successfully using SIP, but may experience one-way or no-way audio.Trunk provider ports – Ports must be forwarded correctly both on the network edge and on the SIP trunk provider’s end of the link. Whenever a VoIP dysfunctionality is detected, the correct forwarding of ports should also be checked.

Quality of ServiceAnother set of voice-related malfunctions are linked to the amount of traffic on the network. A converged network is one where both voice and data traffic share the same infrastructure. Initially, voice services may function with an acceptable level of quality, but as data patterns and data applications change on the network, degradation can occur. This can result in delays in voice transmission, intermittent interruptions, the introduction of jitter and a general decrease in call quality. This is most likely due to either the lack of Quality of Service (QoS) mechanisms on the network, or their inadequate or faulty configuration.

FirmwareFinally, many issues with VoIP are related to how the operating systems and firmware of VoIP devices and servers operate. Vendors continually update their firmware and provide free access to the most up-to-date versions online. IT professionals should upgrade and update device firmware regularly to make sure that any bugs or faults discovered by other users can be proactively dealt with and resolved.

If you still have to call tech support…Even if you do proceed with troubleshooting, there are times when reaching out to the vendor or the telco is necessary. Keep in mind that if you have done the proper preliminary steps and you have gathered the appropriate information, you can substantially cut down on the time it will take the trained techs to solve your issues. When making the call, be sure to have the following information ready:

If a user is complaining about faulty behavior of the telephony system, try to reproduce the fault so you have firsthand experience with it, verify that it is not user error, and be able to better articulate the issue to tech support.

Have the firmware and/or software version numbers of the IP PBX, gateways and any other network equipment handy.

Have the telephone or softphone model numbers or versions along with their configuration and setup on hand.

Depending on the policies of the help desk you are contacting, be ready to provide some supervised access to your system via a remote desktop application.

CONCLUSIONEven though IP telephony shares the same infrastructure as conventional IP data networks, its behavior and troubleshooting methodology is far from similar. For this reason, it is important to be able to identify the problems related to VoIP and to determine more precisely where the fault exists, so it can be pinpointed and resolved more efficiently.

Categories

As a Panasonic authorized reseller, APS is your single source provider of business phone systems in all of Houston and the surrounding areas including: Spring, Klein, Tomball, Magnolia, Cypress, Humble, Atascosita, Clear Lake, Sugarland, Bellaire, Katy, Cypress, The Woodlands and more. APS offers voice & data lines, voice mail, cabling, video conferencing systems as well as the full line of Panasonic products.